Bacterial products are already known which have a therapeutic activity and which are obtained by alkaline hydrolysis. The applicant's patent CH 633 188 discloses for example a concentrate of bacterial lysates having anti-infective properties. The lysates of each bacterial strain are obtained through a progressive alkaline hydrolysis (pH 9-10) which leads to the destruction of the apparent structure of the bacteria.
Actually, the present inventors have established, that bacterial extracts could be obtained having various immunopharmacological properties, such as for example an important immunomodulator activity, by using a different alkaline treatment which makes it possible to retain intact the apparent structure of the treated bacteria. Specifically, this treatment consists in an alkaline extraction using conditions of a high pH and, especially, of a stable pH.